The present invention relates to a wiper controller and a method for controlling a wiper.
A wiper unit for use in an automobile includes a wiper and an intermittent wipe cycle setting device. When the wiper is intermittently wiping a windshield glass, the cycle setting device, which may include a knob, is operated by a passenger to adjust the cycle in which the wiper wipes the windshield (refer to, for example, Japanese Laid-Open Patent Publication No. 10-315919).
The cycle setting device includes a resistor circuit (volume), the resistance value of which varies in accordance with the position (e.g., knob position) of the cycle setting device. The intermittent wipe cycle of the wiper is adjusted in accordance with the resistance value of the resistor circuit.
However, the resistance value of the resistor circuit may differ between cycle setting devices. Thus, when using the resistance value of the resistor circuit to control the intermittent wipe cycle, the wipe cycle may not be properly adjusted. More specifically, the wiper may not be supplied with voltage that is in accordance with the position of the cycle setting device. Thus, the intermittent wipe cycle may not be controlled in accordance with the position of the cycle setting device.
For example, the variance tolerance for the resistance value of the resistor circuit may be ±30% relative to a reference resistance value, as shown in FIG. 4. In such a case, when the cycle setting device is located at a position where the resistance value of the resistor circuit becomes maximum (i.e., maximum wipe cycle position P4) and the reference resistance value at this position is 1000Ω, the resistor circuit may have a resistance value of only 700Ω. This resistance value is less than the reference resistance value of 750Ω for position P3. With such a cycle setting device, even when the cycle setting device is located at the maximum wipe cycle position P4, the wipe cycle of the wiper may not be maximum. Therefore, the wipe cycle must be corrected. However, due to the variance between different cycle setting devices, the correction must be performed for each cycle setting device. Such processing is burdensome.